1. Field of the Invention
This invention relates to suspension systems for automotive vehicles and machines which receive mechanical shock, and more particularly to an anti-swish mechanism for a damper.
2. Description of the Related Art
Dampers are used in connection with automotive suspension systems to absorb unwanted vibrations which occur during driving. To dampen unwanted vibrations, dampers are generally connected between the body and the suspension of an automotive vehicle. A piston assembly is located within the damper and is connected to the body of the automotive vehicle through a piston post which in turn is connected to a piston rod. Because the piston assembly is able to limit the flow of damping fluid within the working chamber of the damper when the damper is compressed or extended, the damper is able to provide a dampening force which "smooths" or "dampens" vibrations transmitted from the suspension to the body.
As the fluid flows in the damper during compression and rebound strokes, the fluid tends to create an audible "swish" noise which is annoying or unpleasant to the human ear. This swish noise is generally heard during low velocity rebound or compression strokes because of the relatively low noise environment during this period. However, swish noise is also sometimes heard during higher velocity strokes. This swish noise generally occurs as the fluid flows through an orifice which causes a flow restriction prior to the fluid entering a bleed or flow port in the piston assembly where the flow restriction is reduced (i.e. bleed section becomes larger or wider). By reducing the flow restriction, a lower pressure or under pressure is created (i.e. Bernouilli's equation) at the entrance point or edge of the bleed or flow port which leads to cavitation of the fluid (i.e. forming vapor bubbles) and the resulting swish noise. With conventional piston assembly designs, this point of low pressure occurs at the entrance edge of the bleed or flow port where the fluid enters the bleed or flow port because it is difficult to supply fluid to this point or edge.
What is needed then is a damper which does not suffer from the above-mentioned disadvantage. This will, in turn, eliminate or reduce the swish noise associated with conventional dampers during compression and rebound strokes. It is therefore, an object of the present invention to provide such an anti-swish mechanism for a damper.